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Madison Vaccine to be Tested in Combination Prostate Cancer Treatment

[Corrected 8/29/14, 8:39 a.m. See below.] Madison Vaccines, a Madison, WI-based startup developing immunotherapies for prostate cancer, will get a chance to see how well its lead vaccine can shrink tumors when teamed up with another drug.

The Phase I trial will be led by Madison Vaccines co-founder Doug McNeel, an oncologist and professor of medicine at the University of Wisconsin-Madison. McNeel and a team of university researchers were awarded a $1.5 million grant to conduct the study. The Movember Foundation is providing the funding through the Movember-Prostate Cancer Foundation Challenge Award program. [An earlier version of this article indicated the grant was awarded to the company. We regret the error.]

Madison Vaccines (MVI) is creating vaccines from tiny circular bits of DNA called plasmids. The company’s lead DNA vaccine, MVI-816, contains instructions for a protein named prostatic acid phosphatase (PAP), which is made by prostate cells. When injected into the skin, the DNA is taken up by the body’s cells, which use the DNA to make copies of the PAP protein. That protein, in turn, acts as an antigen to stimulate an immune response against PAP.

MVI’s lead vaccine, which is entering Phase II trials, has been primarily tested in patients after their prostates have been removed, but before the cancer has spread to the bones or other organs. The idea is to prevent, or at least delay, the onset of metastases and the need for castration by priming the immune system to recognize cancerous cells and kill them.

But the trial funded by the $1.5 million grant, which will begin enrolling patients within a year, will attempt to treat patients with metastatic prostate cancer. MVI’s lead vaccine will be combined with an undetermined PD-1 pathway inhibitor drug, which is designed to keep cancer cells from camouflaging themselves.

These inhibitor drugs have shown promise against some diseases, like melanoma and some lung cancers, but they haven’t worked well against prostate cancer, said MVI co-founder and CEO Rick Lesniewski. McNeel has conducted pre-clinical research that suggests teaming an inhibitor with MVI’s lead vaccine could more effectively treat prostate cancer, Lesniewski said. In theory, the inhibitor would help reveal the cancer cells, and the vaccine would teach the body’s immune system to knock them out.

“We believe this two-pronged immune activation approach, pairing a PD-1 pathway inhibitor with a vaccine, will generate the results we need to have a significant impact on this disease,” McNeel said in a prepared statement.

While MVI moves forward with its separate Phase II trial, the new study could speed up commercialization of MVI’s lead vaccine, Lesniewski said. The Phase II trial will take at least two years, partly because MVI will try to demonstrate that the drug delays the spread of cancer—rather than the typical cancer drug test that aims to shrink a tumor in a matter of weeks or months. But because the new Phase I trial will treat patients with tumors that can be measured, it could face a shorter timeline—assuming the two drugs work as the company and its funders envision.

“If we were to see tumor responses in this trial, which haven’t been seen with PD-1 alone, that could start to reveal a clinical signal that the two are working synergistically together,” Lesniewski said.